Ceiling tile adapted for electrical heating and sound absorption



Oct 1965 N. E. HAGER, JR., ETAL 3,214,565

CEILING TILE ADAPTED FOR ELECTRICAL HEATING AND SOUND ABSORPTION Filed Jan. 30, 1963 2 Sheets-Sheet 1 I N V EN TOR.

NATHANIEL E HAGER, JR- BY JOHN M. HEMPHILL CEILING TILE ADAPTED FOR ELECTRICAL HEATING AND SOUND ABSORPTION Filed Jan. 50, 1963 Oct. 26, 1965 N. E. HAGER, JR., ETAL 2 Sheets-Sheet 2' United States Patent 3,214,565 CEILING TILE ADAPTED FOR ELECTRICAL HEATING AND SOUND ABSORPTION Nathaniel E. Hager, Jr., Manheim Township, Lancaster County, and John M. Hemphill, Lancaster Township, Lancaster County, Pa., assignors to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Filed Jan. 30, 1963, Ser. No. 255,010 1 Claim. (Cl. 219-345) This invention relates to a ceiling tile which is adapted for electrical heating and sound absorption.

The use of ceiling tiles for providing acoustical treatment of living and working areas has become extremely popular in recent years and the advantages of acoustical treatment to living and working areas has become widely recognized in modern construction, such treatment in schools, offices, and homes having become quite commonplace. In addition, the use of panels in ceiling and wall units for providing electrical heating means has become more practical in recent years and thus the advantage of electrical heating has, at the same time, had a significant effect on modern design.

The primary object of this invention is to provide a ceiling tile which is adapted for both electrical heating and sound absorption and which will provide for both acoustical treatment and electrical heating in modern construction. An ancillary object is to provide an integral unit especially designed for ease of installation and maintenance as well as eflicient ceiling heating design with maximum acoustic treatment.

Another object of this invention is to provide a ceiling tile for lay-in type ceiling construction or other types of suspended systems which is both relatively incombustible and inexpensive, such units providing ceilings which are especially effective in case of fire. A further object of this invention is to provide an integral self-supporting ceiling unit which will provide a radiant heating element on the side of the unit facing the area to be heated and which will have a minimum noise reduction coefiicient greater than about .40.

Still another object of this invention is to provide a ceiling tile adapted for electrical heating and sound absorption which is relatively free of electrical shock hazard.

Still a further object of this invention is to provide a unit which will additionally function as a ventilating ceiling tile.

These and'other objects of the invention will be readily understood from the description which follows.

In accordance with our invention, a sheet-type electrical resistance-radiant heating element is secured to the face of a self-supporting backing of acoustical material having sound-absorbing interstices disposed therein and a plurality of sound-absorbing openings are provided extending through the radiant heating element and communicating with the sound-absorbing interstices in the acoustical backing.

Typical of the acoustical materials which may be used for the acoustical tile backing are the board-like products formed from a slurry of mineral wool and/or glass wool and the like in which the fibers are present in clumps and are coated with a starch binder. Another type of acoustical material which may be used in the practice of this invention and which is currently sold in large volumes is the board-like product formed from a waterlaid mat of vegetable fibers, similar to conventional insulating board. Other acoustical materials which may also be used in the practice of this invention are incombustible inorganic cellular glass materials of the type disclosed in US. Patent 2,946,693. In all of these materials there is a self-supporting acoustic backing having a plurality of interstices in the body of the acoustical backing which provide a means by which sound is attenuated and absorbed.

A metallic foil is preferred as the sheet-type electrical resistance radiant heating element although it will be readily evident to those skilled in the art that other sheettype electrical resistance radiant heating elements such as a continuous electrical resistance metallic film deposited on a suitable insulating layer or directly upon the surface of the acoustical backing could be used.

A laminated heating sheet of the type disclosed in US. patent application Serial No. 132,496, filed August 18, 1961, would provide a suitable electrical resistance radiant heating element, the sheet being adapted to be punched through without shorting. Such sheet would additionally provide a ground sheet between the living space andthe live sheet to reduce electrical shock hazard.

When using a sheet-type electrical resistance radiant heating element, a grounded electrically conductive sheet may be placed over the heating element if desired and insulated therefrom by suitable means such as an inter leaf of insulating paper to reduce shock hazard. Also, by suitable choice of heater design the unit may be run on 20 or 30 volts or whatever is deemed sufliciently low so that shook hazard is considered negligible.

In preparing the ceiling tile units in accordance with this invention, the sheet-type electrical resistance radiant heating element, such as a serpentine foil heater, may be secured to the face of the acoustical backing member by any suitable means such as adhesive or mechanical fastening means.

In the fabrication of the combined electrical heating and sound-absorbing units, a plurality of sound-absorbing openings are provided extending through the facing and communicating with the sound-absorbing interstices in the acoustical tile backing material. These may be providedby punching or drilling holes or fissures through the heater into the interior of the acoustical backing to provide for the absorption and attenuation of sound waves. The punching or drilling of the plurality of holes or openings through the heater element provides for the openings for the passage of sound waves and does not interfere with the heating functionof the heating element as long as the electrical resistance heating circuit is not disrupted and the' heating element in turn does not impair the acoustical functioning of the unit.

In order to provide a decorative surface layer, paint may be applied directly to the heater-faced acoustical material. Also, a decorative surfacing layer of an opaque sheet of plastic, fabric, or other suitable material which does not appreciably interfere with sound absorption or radiant heating, may be provided over the surface of the combined heating and acoustical panel to provide a decorative finish. Where decorative material is attached directly to the face of the ceiling tile, the punching operation or drilling operation which provides the sound-absorbing openings communicating with the interstices in the body of the acoustical material may be performed after the decorative sheet material is secured to the facing. As an alternative, the decorative facing sheet may be secured as a membrane to the ceiling tile by securing only the edges of the sheet to the panel after the punching or drilling operation has been performed.

In order to provide for year-round air conditioning, air ventilating holes may be drilled or punched completely through the combined heating and acoustical units and a plenum chamber formed in back of the ceiling unit used to supply conditioned air to the room year round.

The invention will be more fully understood and further objects and advantages thereof will become apparent when reference is made to the more detailed descrip- Patented Oct. 26, 1965" tion of preferred embodiments of the invention which follows and to the appended drawings in which:

FIGURE 1 is a top plan view showing the basic elements of a ceiling tile embodying the invention;

FIGURE 2 is a sectional view taken on line II-II of FIGURE 1;

FIGURE 3 is a partial top plan view of a modified ceiling tile having additional air distributing holes drilled therethrough; and

FIGURE 4 is an enlarged sectional view taken on line IV-IV of FIGURE 3.

Example 1 A 12" x 12" acoustical tile formed from a slurry of modulated mineral wool fibers and starch binder was sanded to about thickness and faced with a sheet of 0.0008" copper foil 2 using a rubber-resin adhesive to bond the foil to the tile. The foil was cut in a serpentine pattern as shown in FIGURE 1 leaving tabs extending from the foil heater at 3 and 4 as electrical connecting means. A clear film 5 of polyethylene teraphthalate was adhesively secured over the facing of the foil-faced acoustical tile. The film-faced unit was then punched, as indicated at numerals 6 and 7, with .050" and .100" punches in the pattern shown in FIGURE 1, the punches forming sound-absorbing openings, shown more clearly in FIG- URE 2, extending into the acoustical tile backing 1 and communicating with the sound-absorbing interstices therein.

The heater was connected to a source of current and at a current of about 12.8 amps the heater gave off 68 B.t.u.s per hour or 20 watts per square foot with a heater temperature of about 36 F. above ambient. The noise reduction coefficient (N.R.C.) of the unit, which is the average of the sound absorption coefiicients measured at 250, 500, 1,000 and 2,000 cycles per second, was 0.66. The same acoustical tile backing, but without the foil heater and film facing, punched with the same configuration shown in FIGURE 1 using the same size punches, has an average N.R.C. of about 0.73..

A modified unit constructed in accordance with Example 1, but having additional air metering openings 8 extending between the facing and back surfaces, is illustrated in FIGURES 3 and 4. By combining the source of air conditioning andheating means in the ceiling units, a greater control over even over-all heating is realized.

Example 2 24" x 48" lay-in type acoustical panels, felted from a slurry of mineral wool, inorganic filler, and starch binder on a Fourdrinier machine, were used in fabricating a number of acoustic-electrical heating units. The panels, which were sanded to a thickness, were covered with a sheet of 0.0008" thick copper foil using a rubber-resin adhesive to bond the foil to the panels. The foil was then cut in a serpentine pattern having 1% wide strips of copper foil as the heating elements and a 1" border around the edge of the serpentine foil heater. The foil-faced acoustical tiles were then punched with .050 and .100" pins in the pattern shown in FIGURE 1, the punches forming sound-absorbing openings extending into the acoustical tile backing and communicating with the soundabsorbing interstices therein. No. '14 copper wire leads were passed through the back of the tile and soldered to copper platelets secured at each end of the serpentine heater circuit. A 0.5 mil film of polyethylene teraphthalate printed with an opaque grey and white pattern was adhesively secured to the sides of the tile unit and heat shrunk to yield a smooth plastic face.

Resistance measurements were taken on the heaters, before and after punching. The resistances of the heaters ranged from .638 to .669 ohms before punching, with an average resistance of .650 ohm, and ranged from .713 to .761 ohms after punching, with an average resistance of .729 ohm. After installation, thermocouples placed on the plastic facing, with the current on, and at an ambient temperature of 76 F., typically indicated surface temperatures of F. to F. Using a current of about 18 amps, the panels gave off heat of about 35 watts per square foot. Of the total heat transferred by the units, about 80% is transferred to the room being heated.

The units had average N.R.C.s of greater than about .60 whereas commercial acoustical tiles of the same composition faced with plastic but without heating elements have average N.R.C.s of about .69.

The ceiling units of this invention which are adapted for both electrical heating and sound absorption have certain inherent advantages over the prior art. The units have a quick response, the plastic, painted, or other decorative surfaces having only a negligible insulating effect while the acoustical backing-materials offer additional insulating value thus forcing the heat in the desired direction. The ceiling systems are readily adaptable to allow ready handling of changes in load by rewiring or relocating ceiling units. Lay-in type ceiling installations will allow for considerable accessibility for needed changes and repairs. Units will be factory made and tested and will require minimum labor for installation.

We claim:

A ventilating ceiling tile adapted for electrical radiant heating and sound absorption and having a noise reduction coefiicient greater than .40 comprising a backing'of acoustical material having sound-absorbing interstices disposed therein, a sheet-type electrical resistance radiant heating element secured as a facing to said backing, a plurality of sound-absorbing openings extending through said radiant heating element into the interior of the acous: tical backing and communicating with the sound-absorbing interstices in the acoustical backing, and a plurality of air metering openings extending completely through both the heating element facing and the acoustical backing.

References Cited by the Examiner UNITED STATES PATENTS 2,455,926 12/48 Gessler et al 296-137 2,615,115 10/52 Watter 219-377 2,677,749 5/54 Raider 219-345 X 2,719,213 9/55 Johnson 338-212 2,721,731 10/55 Rapp 181-33 2,771,164 11/56 Scurlock 219-345 X 2,785,099 3/57 Holtsford 1'81-33 2,952,761 9/60 Smith-Johannsen 219-541 2,992,351 7/61 Van Dan Heuten et al. 181-33 3,137,364 6/64 Akerson 181-33 3,143,637 8/64 Rifenbergh 219-345 3,147,926 9/ 64 Rosenblatt 240-9 FOREIGN PATENTS 1,257,121 2/61 France.

713,684 8/54 Great Britain.

RICHARD M. WOOD, Primary Examiner. 

